If there is anything designed in this whole picture, it is that hamburger. Designed by humans for human consumption. The meat has been ground at first, then broiled or otherwise prepared. We can design anything we want to suit ourselves: Instead of caves, we live in houses. We cannot fly, so we buildplanes. We are not designed, we are the designers.

Are humans, as animals, meat eaters? We do have quite a wide range of teeth. The incisors are, in my opinion, pretty clear evidence of this, though the issue is not their sharpness. We have top and bottom incisors, and each set is essentially a wedge with a semi-sharp edge. Together with our mandibular strength, these become pretty powerful ripping tools. If Ozzy Osbourne can bite the head off a live bird, I think they're sharp enough to make the point. (BTW: those who argue that human teeth are NOT sharp have clearly never stuck their fingers in a teething baby's mouth--ouch!)

On a different and more compelling front, humans need lysine, a critical amino acid, in order to properly manufacture proteins in our bodies. We can't make lysine on our own--we have to get it from our diet. Guess what? Animal flesh is one of the most important sources of lysine. (Cholesterol--another byproduct of eating animals--is also essential to brain growth in infants and young children. ) Of course, today's vegetarians and vegans can get such things from basic vitamin supplements, and more power to them. The argument that you don't have to eat meat just because you're designed that way is a good one and works for a host of things. But the other argument--that meat tastes so, so very good--is enough for me. Grab yourself a Kansas Citytenderloin, throw it on the fire, open a nice bottle of Cabernet Sauvignon, and enjoy!

Well, this certainly isn't an argument which is going to fade away any time soon. And this is OK. Re Footprints' argument: I agree wholeheartedly that just because we CAN do a thing, it is not necessarily therefore moral to do a thing. I can take a knife and stick it into the gut of a random pedestrian, but human culture has decided that this is a crime and a sin. The point about babies, though designed to provoke a visceral reaction, is a little more complicated. It is possible, for example, to make arguments about perpetuating the species. And as our own children are the vessels in which we transmit our genes to eternity, I suspect there's a built-in reaction against this as well (though stronger in some than in others).

Of course, the above is far from a watertight logical argument. But it does highlight the fallacy of making moral arguments about vegetarianism.

Whenever this comes up within earshot, I keep thinking of a Bloom County comic strip where Binkley has hung himself upside-down in a tree with a handkerchief over his mouth to stop himself from "massacring millions of innocent germs." One has to draw the line between killable and non-killable life forms somewhere; why should it be any less ethical to draw it just below human beings than just above plants?

Jaw & Facial muscles:Carnivores have evolved have wide mouths in relation to their heads and reduced facial musculature- it's an aid in killing prey. We've got a mouth cavity and jaw muscles made for chewing, like many herbivores.

Saliva:Mammalian carnivores don't use saliva.
Human beings have carbohydrate-digesting enzymes in their saliva, which might suggest that we're adapted for eating all those animals made of carbohydrates, like the uh, er... um...

Digestive tract:
Carnivores have a short and smooth colon. Stomachvolume of a carnivore is 60-70% of total digestive system capacity, with a stomach pH of 1. Their digestive tract is designed to extract nutrients quickly and expel waste quickly before putrefaction sets in. Humans have a small intestine about 10 to 11 times body length, a stomach pH about 4 or 5. Our digestive tract is adapted to hold food in for long periods of time to maximize the extraction of nutrients (from difficult to break down molecules like cellulose from plants).

Liver and kidney:
I don't pretend to understand the significant difference between bile secretion in carnivores vs. herbivores. I do know that carnivores use the enzyme uricase to break down the non-metabolizable uric acid found in flesh. Human beings lack this enzyme, and absorb and excrete uric acid with our kidneys.

1) Evolution and design are not incompatible. For instance, our eyes don't happen to be good visual organs by chance. They have been designed for the purpose of seeing by milions of years of natural selection.

2) Humans are designed to be able to eat animals (and to enjoy it, if they are nicely cooked). We are generalists, we are designed to be flexible, to cope with a wide range of habitats and food sources (mostly by building tools, but that's another node). We are also able to eat each other, kill each other, etc. Just because we can, doesn't necessarily mean that we should. Just because we like it doesn't mean we should, either.

More importantly, we are capable of living on a meat-free or nearly meat-free diet for most of our lives without much trouble. Human beings are not designed to require eating animals.

Sorry, but our canine teeth are not sharp. Carnivore's and omnivore's canine teeth are long, sharp, and curved -- they are also spaced out from the other teeth so fibrous strips of flesh don't get caught between them. Herbivore's canine teeth are dull and usually short, but long in some animals such as the hippopotamus for defense. So, how are human canines shaped? They are short and blunted, just like most herbivore's -- they are also right next to the other teeth, not spaced out as in carnivores and omnivores. They are perfect for peeling things such as fruits and vegetables, but not for shredding meat.

Although humans are able to eat meat, when compared to carnivorous, omnivorous, and herbivorous animals, we most closely resemble the herbivorous ones. We are capable of living solely on a plant-based diet and getting all of the nutrients and vitamins we need.

"One has to draw the line between killable and non-killable life forms somewhere; why should it be any less ethical to draw it just below human beings than just above plants?"

I have heard this argument by a lot of people who think vegetarians or vegans are making a contradiction in their lifestyle. Why not stop eating plants also, they are also living things? Well, you're missing the big point. There is no evidence that plants can feel pain, so in turn, they cannot suffer. On the other hand, animals do feel pain, therefore they can suffer.

Most people eliminate meat, or all animal products from their diet, because they don't want to contribute to any suffering. It has nothing to do with "killable and non-killable life forms", as you put it.

"On a different and more compelling front, humans need lysine, a critical amino acid, in order to properly manufacture proteins in our bodies. We can't make lysine on our own--we have to get it from our diet. Guess what? You get it from eating animal flesh. (Cholesterol--another byproduct of eating animals--is also essential to brain growth in infants and young children.) Of course, today's vegetarians and vegans can get such things from basic vitamin supplements, and more power to them."

100% of the cholesterol humans need is produced in their own liver. Any cholesterol that you intake from your diet is excess (not that that's bad in limited amounts.) How many people do you know have served their infants steak because they were worried about them not getting enough cholesterol?

Regarding Ereneta's argument above: The idea to list the features humans have in common with herbivores and carnivores is a good one. However, you left out some key facts. For example, you mentioned cellulose. Human beings cannot digest cellulose (fiber) which is a key nutrient for purely herbivoric animals. Indeed, the appendix, which facilitates cellulose breakdown in herbivores, is nonfunctional in humans, which is why fiber runs right through my system. It is clear from this and from the other facts you pointed out that humans are biologically adapted to be omnivores - we literally eat everything. Prehistoric records show us that mankind has eaten the flesh of animals since the dawn of our species; it is postulated that an ancestor of modern humans drove the american mammoth to extinction. In summary, we are well-adapted to eat meat so it tastes good so I eat it because it's not "wrong" because in order for life to survive, living things must die. Thank you.

From a dental standpoint, humans' teeth are equally suitable for eating meat
and plants. We have incisors, capable of cutting into meat and vegetable
matter, canines (not present in herbivores) suitable for tearing meat, bicuspids
suitable for grinding and tearing meat and vegetables, and molars suitable for
grinding both again. Our saliva contains enzymes such as lipase and
amylase, fat- and protein-reducing enzymes suited more to a carnivorous
diet. Yet, as Erenteta quite rightly pointed out, our digestive tract is more
suitable for a herbivorous diet. Our jaws also move horizontally as well as
vertically, a feature in many herbivorous (and omnivorous) animals and relatively few
carnivores. All in all, we're a bit of a mixed bag of a species.

Consider the following point, however. Mammalian herbivores have evolved
with their eyes on either side of their heads, providing almost a 360-degree
field of vision. Herbivores tend to be docile (in general), and are therefore
likely prey for their carnivorous predators. Their wide field of vision
enables them to eat and to keep a constant watch-out for predators. Witness the
antelope, mouse and even the rhinoceros for proof.

Carnivores and omnivores, on the other hand, have evolved with eyes at
the front of the head, with an overlapping field of vision. This provides
stereoscopic vision with depth-perception, essential when chasing down prey or
sizing up a potential kill. And guess what? Humans fall into this category,
along with tigers, wolves and countless other heartless killing machines.

We have evolved as hunters. Over the millennia, our intelligence has enabled
us to create weaponry and clothing, changing us from apish, feral, hairy
primates to the weak, relatively defenceless species we are today. Surely that
is evolution? Some birds started to build nests, so they evolved to be dependent
upon nests. We don't accuse them of assuming control of their own destiny. An
interesting effect of our intelligence is that we are able to design new
diets capable of supporting us without the consumption of meat, even though we
as a species have been eating meat since time immemorial.

The Romans ate meat, as did the Abyssinians, the Ancient Egyptians, the
Ancient Greeks and countless other civilizations. Humans ate meat then and we
are eating meat now, so the "suggestions" made by our physiology are
nothing more than that. Suggestions towards a situation (humans as herbivores)
proven patently incorrect by human history.

To sum up, primitive humans evolved to hunt, ergo to eat meat (in addition to
plants). Our intelligence has hastened our evolution, weakening our bodies while
sharpening our minds. And this rapid evolution has resulted in our ability to
choose to be vegetarians (apologies to sufferers of animal protein intolerance
who clearly have no such option). To me, the option to be vegetarian is little
different to the option to use recycled products - it is an option, some
people feel compelled - for a variety of perfectly good reasons - to take it,
and no-one should be criticized for it.